1. Field of the Invention
The present invention relates to pumps, and, in particular, to gear pumps.
2. Description of the Related Art
FIG. 1 is a schematic illustration of an exemplary prior art gear pump 100. Such a pump 100 typically includes a casing 111 and a pair of rotors 113, 115, with intermeshing gear teeth 117. The casing 111 defines an inlet port 107 and an outlet port 108, which extend in a generally radial direction with respect to the rotors 113, 115. Fluid is carried from the inlet port 108 in spaces (or chambers) 102 that are formed between the gear teeth of the rotors. The fluid in these chambers 102 is displaced as the teeth engage with the teeth of the opposing rotor and the fluid is displaced out the discharge port 108.
Such conventional gear pumps are simple and relatively inexpensive, but suffer from a number of performance limitations. A source of problems with conventional gear pumps is in the area where the teeth 117 mesh and create a seal 104 between the inlet and discharge ports 107, 108. Conventional gear pumps use conventional gear tooth profiles such as would be used in a geared power transmission device. This type of gear configuration is well suited for power transmission, but has significant limitations when used to pump incompressible fluid.
A need therefore exists for an improved gear pump which addresses at least some of the problems described above.